Metal composition



siderable and important Patented May 5, 1931 PATENT OFFICE RICHARD R. WALTER, O1- NURETMBERG, GERMANY METAL COMPOSITION No Drawing. Application filed November 21, 1927, Serial No. 234,897, and in Germany September 1, 1927.

My invention pertains t'oa metal compdsition partially produced by a process for condensing or consolidating a powdered metallic aggregation or coherent mass of pow- 5 dered particles, or sintered metal body.

The formation of metals or metal compounds or combinations with a high melting point, including tungsten, molybdenum, tantalum and others or their metallic com- 10 binations with other elements, usually occurs by'compression of the powdered and sintered ingredients at high temperatures.

Such sintered bodies composed of powdered materials are known and to the naked 15 "eye disclose an apparently ultra dense texture, but in reality the are in most cases not a homogeneous metallic mass or true alloys, rather, the individual dust particles of the prepressed bodies produced by the sintering process are only stuck together and as microscopically viewed, highly magnified, these sintered metal bodies also reveal, throughout a cross-sectional plane, a structure with many cavities. 7 r

:1 In order to improve the density of metal powders having a high melting temperature additions of other metals in powdered form haveheretofore' been made, notably, metals like nickel andcobalt which have a lower melting point than the main mass. However, the results of that method for lessening the cavities have proven insuflicient because such additions merely effect a better agglutination or frit or what might be termed a partial high come liquefied at the usually employed sintering temperatures ranging between fifteen hundred and eighteen hundred degrees cen- 40 tigrade.

One object of the present invention is to avoid the drawbacks such as porosity and inadequate mechanical tenacity which till now have been associated with sintered metal bodies. I have discovered'that a sintered metallic mass, for example of tungsten or either tungsten or molybdenum carbides or nitrides and'produced according to the well-known manner as above described can exercise a concapillary action if sorption is comparatlvely gredient particles fusion of the particles of the constituents of melting temperature which cannot bebrought into contact with fluid metals or fluid alloys, in consequence of theextraordinar minute porosity which is uniformly distri uted throughout the sintered metal body though not detectable to the naked eye.

Actually, such sintered metal bodies suck up the molten metal with so pronounced a capillary power that they become homogeneously permeated therewith. My invention may, for example, be conveniently practiced by laying nickel or chromium singly or together or other metals singly or together upon a sintered metal mass and then heating the whole until the superimposed metal melts. When that occurs the molten metal disappears in a few seconds and the sintered mass will have completely absorbed it. The absorption is not dependent upon a superimposed contact.

The occurrence may be compared with a lump-of sugar upon which a dro of fluid is deposited to have its moisture ecome u-niformly distributed throu hout the, entire lump. Naturally, the'cap'llary power of abfar greater in the case of sintered metal bodies because of the correspondingly greater finenessof the inor granules.

[The density and. homogeneity of a powdered metal .mass or of metallic combinations edly greater than if the same ingredients be chosen and merely sintered together in powdered condition. When the volume of the sintered or otherwise aggregated or agglutinated metallic mass remains the same and yet has had to encompass additional metal by. the

described liquation and capillary absorption, it is inevitably established that the density must have correspondingly increased. It has been learned that sintered metallic masses can absorb by capillary liquation twenty per cent .or more oftheir own weight of other metal,

without altering their exterior shape.

treated according to this invention are mark.-

mechanical firmness of the sintered metal body'to occasion a cracking or bursting of the latter. Accordingly, for every sintered metal body there is a best or preferable receptivity up to which it will maintain its shape without danger.

Besides increasing the density of metallic bodies, my process will considerabl enhance their mechanical firmness and above all their resistance to wear and, accordiiig to the choice of the metal or metals to be absorbed, likewise their hardness.

I would have it understood that the scope of my invention is not requiredto be limited in consequence of my description pertaining 4 to sinteredbodies which was merely selected 0 exemplify one successful adaptation for producing an alloy with certain desired attributes; nor need the pre-formed aggregation be one metal, nor a mixture of several nor a compound or combination of several with other chemical elements. Variations in the number of metals to' be melted and ab-' sorbed and of the chemical groups to which they may belong and of the required temperatures suited thereto are recognized to be feasible and comprehended by. the range of'novelty. For instance, if a moltenalloy which itself possesses value for cutting purposes be absorbed, the fitness of the eventual product for cuttingpurposes is correspondingly improved;

V I, claim 1. In a metal composition capable of resisting wear during use for cutting, the combination of metal particles including tungsten and fritted to each other into a coherent mass having minute cavities between said particles and afilling of an alloy in said structure cavities, said alloy including a metal of the iron group and a metal of the chromium group and, constituting about twenty per cent by weight of the tungsten -mass.

2. A metal composition capable of resisting wearduring use for cutting, comprising tungsten nitride particles fritted to each other in the form of a coherent porous structure and an alloy including cobalt and a metal of the chromium group filling the voids in said structure.

3. A hard yet tenacious'metal composition of particles of a tungsten combination preformed as a sintered mass of predetermined porosity and an alloy of metals of the iron and chromium groups respectively, said alloy being of lower melting temperature than said tungsten combination and of sufliclent quantity to fill the pores therein.

Signed by me, this 18th day of November,

RICHARD R. WALTER; 

